Consider the following points:
(a)All excavates live in environments where oxygen availability is low;(b)all excavates lack mitochondria;and (c)all excavates have some mitochondrial genes.Based on this information,which of the following statements is true of the excavate lineage?
A)Their ancestors were eukaryotes that existed prior to the origin of mitochondria.
B)Their ancestors had mitochondria,but the mitochondria were lost over time.
C)Their ancestors were not able to metabolize glucose.
D)Excavates are in the process of acquiring mitochondria through evolutionary adaptation.

Question

Quizplus · Accepted Answer

The fact that all excavates have some mitochondrial genes suggests that their ancestors had mitochondria, but they have lost them over time. The low oxygen availability in their environments may have led to the loss of mitochondria in order to avoid the production of toxic reactive oxygen species. The presence of mitochondrial genes may be vestigial remnants of their ancestor’s mitochondrial genome.

Consider the Following Points